The lipid nanoparticle is a protective envelope that allows the mRNA to survive long enough until it can be endocytosed into a cell. No, the brief presence of the mRNA for a few hours inside a cell is not an infection. By definition, an infection is the process by which a virus enters a cell and takes over its function. In order to establish an infection, a virus uses a number of proteins which simply are not present in a liposome coated mRNA particle.
Viruses, FYI, are also encased in lipids. Viruses use their spike (or equivalent, in other virus species) protein to attach to the outside of the cell. Once the cell engulfs them, they quickly disable the normal functions of the cell and force it to make virus mRNA, genome, and proteins and assemble them into new virus particles. That's all that cell does until it is so full of millions of virus particles that it bursts open.
Given a choice between a simple vaccine that causes the production of an antigen for a few hours and a viral infection that literally takes over millions/billions of cells in my body and turns them into virus factories before killing them, I'll choose the vaccine.
Except that it's not a few hours, there is research showing it is a few months and it winds up in tissues that are never touched by a normal viral infection.
And you already destroyed your credibility by equivocating eating a steak to getting an injection.
And normal vaccines are better than getting the disease because they work. The vaccinated people I know get COVID several times a year. Vanishingly few "unvaccinated" people have had more than one infection and those that do measure the time between infections in years, not weeks.